Bug#697727: xserver-xorg-video-radeon: [radeon] Scrolling in xterm slow with KMS

[Tilo Schwarz]

On Wed, 09 Jan 2013 13:06:36 +0100, Michel Dänzer <daenzer at debian.org>  
wrote:

> On Die, 2013-01-08 at 23:20 +0100, Tilo Schwarz wrote:
>>
>> Scrolling in an x-term is much slower than before (it is clearly
>> noticeable by eye).
>>
>> Investigation shows, that scrolling is about 5 times slower when KMS is  
>> on.
>>
>> A "time seq 100000" takes about 12 seconds with
>> "options radeon modeset=1" in /etc/modprobe.d/radeon-kms.conf.
>>
>> A "time seq 100000" takes about 2-3 seconds with
>> "options radeon modeset=0" in /etc/modprobe.d/radeon-kms.conf.
>>
>> xterm and rxvt show the same effect.
>
> [...]
>
>> [    56.923] (II) RADEON(0): KMS Color Tiling: enabled
>
> Sounds like https://bugs.freedesktop.org/show_bug.cgi?id=34486

Hi Michel,

thank you for the reply:

Indeed, using

% grep ColorTiling /etc/X11/xorg.conf
         Option          "ColorTiling"   "off"

the scrolling is twice as fast as without this option (from 12sec down to  
6sec). That is still almost three times slower than without KMS, but  
already much more usable!

What worries me is, that now I get the following error messages, whenever  
I switch tags (using awesome WM, tags are like virtual desktops):

r300: I got a pre-allocated buffer to use it as a texture storage, but the  
buffer is too small. I'll use the buffer anyway, because I can't crash  
here, but it's dangerous. This can be a DDX bug. Got: 7114752B, Need:  
7119360B, Info:
r300: texture_desc_init: Macro:  NO, Micro: YES, Pitch: 1728, Dim:  
1678x1029x1, LastLevel: 0, Size: 7119360, Format: s8_uint_z24_unorm
r300: I got a pre-allocated buffer to use it as a texture storage, but the  
buffer is too small. I'll use the buffer anyway, because I can't crash  
here, but it's dangerous. This can be a DDX bug. Got: 176128B, Need:  
179712B, Info:
r300: texture_desc_init: Macro:  NO, Micro: YES, Pitch: 1728, Dim:  
1678x25x1, LastLevel: 0, Size: 179712, Format: s8_uint_z24_unorm
r300: I got a pre-allocated buffer to use it as a texture storage, but the  
buffer is too small. I'll use the buffer anyway, because I can't crash  
here, but it's dangerous. This can be a DDX bug. Got: 7114752B, Need:  
7119360B, Info:
r300: texture_desc_init: Macro:  NO, Micro: YES, Pitch: 1728, Dim:  
1678x1029x1, LastLevel: 0, Size: 7119360, Format: s8_uint_z24_unorm
r300: I got a pre-allocated buffer to use it as a texture storage, but the  
buffer is too small. I'll use the buffer anyway, because I can't crash  
here, but it's dangerous. This can be a DDX bug. Got: 176128B, Need:  
179712B, Info:
r300: texture_desc_init: Macro:  NO, Micro: YES, Pitch: 1728, Dim:  
1678x25x1, LastLevel: 0, Size: 179712, Format: s8_uint_z24_unorm
r300: I got a pre-allocated buffer to use it as a texture storage, but the  
buffer is too small. I'll use the buffer anyway, because I can't crash  
here, but it's dangerous. This can be a DDX bug. Got: 7114752B, Need:  
7119360B, Info:
r300: texture_desc_init: Macro:  NO, Micro: YES, Pitch: 1728, Dim:  
1678x1029x1, LastLevel: 0, Size: 7119360, Format: s8_uint_z24_unorm
Failed to open VDPAU backend libvdpau_r300.so: cannot open shared object  
file: No such file or directory
r300: I got a pre-allocated buffer to use it as a texture storage, but the  
buffer is too small. I'll use the buffer anyway, because I can't crash  
here, but it's dangerous. This can be a DDX bug. Got: 176128B, Need:  
179712B, Info:
r300: texture_desc_init: Macro:  NO, Micro: YES, Pitch: 1728, Dim:  
1678x25x1, LastLevel: 0, Size: 179712, Format: s8_uint_z24_unorm

Maybe related to https://bugs.freedesktop.org/show_bug.cgi?id=42085

Now I hesitate to switch ColorTiling off, because a "buffer is too small"  
warning sounds not too good to me ...

Thank you!

Regards,
	Tilo